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The worldwide continual reinforcement of regulations for the production of cleaner fuels along with the larger demand for energy urge us to develop hydrotreatment sulfide catalysts exhibiting higher activity in hydrodesulfurization reactions and explore innovative synthesis strategies. In this work, a novel one‐pot synthesis method of unsupported NiMoS catalysts in water at ambient pressure and moderate temperature is described. The reaction conditions including pH variations and addition of a copolymer structuring agent were thoroughly investigated. Catalytic performances of the prepared bulk NiMoS catalysts were measured for the hydrodesulfurization of two model sulfur molecules, representative of FCC gasoline. Catalysts prepared at pH 7 without or with polymer exhibited roughly similar activity, resulting however from different characteristics favorable for catalyst efficiency probably compensating one another, i. e. a very high promotion rate for the first one and smaller particles along with larger specific surface area for the second. [ABSTRACT FROM AUTHOR]

Several CoMoS/carbons were successfully synthetized using hydrothermal-type approaches and a subsequent surface reaction for the promotion step with Co. The effect of the microstructure of carbons used as a matrix for CoMoS-based catalysts was studied in the case of hydrotreating reactions. It was found that 1D (nanofibers/tubes) or 2D (nanosheets) carbon nanostructures may influence the characteristics of the CoMoS crystallites (dispersion, promotion rate and orientation of the slabs) and as a consequence the catalytic properties. In particular, the HDS mechanism of the substituted 4-MethylDiBenzoThiophene (4-MDBT) was found to be microstructure-dependent, as well as the selectivity of 3-MethylThiophene (3-MT) HDS/2,3-DiMethylBut-2-eNe (2,3-DM2BN) hydrogenation. [ABSTRACT FROM AUTHOR]

Hierarchically porous materials offer the opportunity for catalyst development in regards to improving catalytic performances. In the present work, the combination of latex synthesis, sonochemical reduction and two-step catalysed sol-gel process has been demonstrated to be a versatile method for preparing supported catalysts with tailored hierarchical porosity. This method has been used to prepare porous Pt/SiO2 catalysts with mesopore and macropore size ranges as large as 2-15 nm and 90-400 nm, respectively. These hierarchically porous catalysts presented an excellent catalytic performance for the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). Selectivity values up to 100% at 80% conversion of p-CNB and initial reaction rates up to 74.0 molCNB/min molPt were obtained, while a commercial catalyst exhibited both a lower selectivity of 90.8% and a lower initial reaction rate of 47.7 molCNB/min molPt. [ABSTRACT FROM AUTHOR]

Abstract: Iodo-terminated polystyrene and poly(methyl acrylate) (PMA-I) were synthesized by reverse iodine transfer polymerization. The resulting polymers were coupled by atom transfer radical coupling using Cu(I)/linear amino-ligand catalysts in the presence of reducing Cu(0). The efficiency of the coupling reaction is discussed as a function of various factors, namely, the Cu(0) particle sizes, the number of nitrogen present in the ligand structure, the type of halogen associated with Cu(I) (CuX, X=I, Br, Cl), the nature of the polymer and the nature of the chain ends. In particular, a quantitative coupling (100%) was obtained with a CuBr/HMTETA system in the presence of nanosized Cu(0) for PMA-I, thus opening for the first time a facile route to telechelic and multiblock poly(acrylate)-based structures. [Copyright &y& Elsevier]

Precious metals, in particular Pd, have a wide range of applications in industry. Due to their scarcity, precious metals have to be recycled, preferably with green and energy-saving recycling processes. In this article, palladium extraction from an aluminosilicate-supported catalyst, containing about 2 wt% (weight%) of Pd (100% PdO), with supercritical CO2 (scCO2) assisted by complexing polymers is described. Two polymers, p(FDA)SH homopolymer and p(FDA-co-DPPS) copolymer (FDA: 1,1,2,2-tetrahydroperfluorodecyl acrylate; DPPS: 4-(diphenylphosphino)styrene), were tested with regards to their ability to extract palladium. Both polymers showed relatively low extraction conversions of approximately 18% and 30%, respectively. However, the addition of piperidine as activator for p(FDA-co-DPPS) allowed for an increase in the extraction conversion of up to 60%. [ABSTRACT FROM AUTHOR]

Palladium (Pd) and platinum (Pt) are extensively used as catalysts in the petrochemical and automotive industries, and due to high demand for them on the market, their recycling from spent supported catalysts is clearly needed. To assess the content of Pd and Pt in catalysts in order to establish their commercial value or to evaluate the recovery efficiency of technologies used for recycling, reliable analytical methods for determination of these elements are required. Spectrometric methods, such as inductively coupled plasma optical emission spectrometry (ICP-OES) and graphite furnace atomic absorption spectrometry (GFAAS) are powerful tools that can be employed for the determination of Pd and Pt in various sample matrices. However, these methods allow only the injection of liquid samples. In this regard, the digestion of solid sample by microwave-assisted acid extraction procedures at high pressures and temperatures is often used. In this study, a microwave acid digestion method was optimized for the extraction of Pd and Pt from spent catalysts, using a four-step program, at a maximum 200 °C. The resulting solutions were analyzed using ICP-OES, at two different wavelengths for each metal (Pd at 340.458 and 363.470 nm, and Pt at 265.945 and 214.423 nm, respectively) and using GFAAS (Pd at 247.64 nm, Pt at 265.94 nm). Five types of spent catalyst were analyzed and the standard deviations of repeatability for five parallel samples were less than predicted relative standard deviations (PRSD%) calculated using Horvitz's equation for all the analyzed samples. [ABSTRACT FROM AUTHOR]

• CO 2 -soluble Pd-complexing polymers bearing pyridine units have been synthesized. • Cloud point curves of the polymers have been determined in dense CO 2. • Extraction of Pd from supported catalysts was performed in CO 2 at 40 °C and 25 MPa. • Strong effect of the Pd oxidation state on extraction in CO 2 was reported. • 73 % of Pd was extracted from the catalytic support by the complexing polymers. Precious metals, in particular palladium (Pd), have a wide range of daily applications, from automotive catalysts to fine chemistry production. Nevertheless, these metals are relatively rare and highly expensive, considering their massive industrial utilization. In the last decades, different recycling methods have been explored. Nowadays, the most applied methods, namely pyro- and/or hydrometallurgy, involve energy-intensive processes and/or the generation of large amounts of effluents to be treated. Thus, the development of a more sustainable recycling process of precious metals is highly desirable. In the present work, we introduce a sustainable process based on the use of a green solvent, supercritical CO 2 , operated under mild conditions (P = 25 MPa and T = 40 °C). The extraction process is possible thanks to the addition of CO 2 -soluble complexing polymers bearing pyridine units. The proposed method leads to the extraction of more than 70 % of Pd from an aluminosilica-supported catalyst. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Combination of miniemulsion polymerisation and sol-gel method for catalyst tailoring. • A Pd/SiO 2 catalyst with hierarchical micro-, meso- and macroporosity is prepared. • Catalyst structure withstands pressure conditions in the H 2 O 2 direct synthesis. Abstract The production of hydrogen peroxide H 2 O 2 , as an important commodity chemical, attires the attention towards greener processes such as the direct synthesis from hydrogen H 2 and oxygen O 2 , the selectivity being the biggest challenge. Since this reaction is structure-sensitive, the design of appropriate catalysts is required. We propose a novel method to prepare hierarchically porous Pd/SiO 2 catalyst by combination of miniemulsion polymerisation to prepare a Pd-containing latex template and sol-gel synthesis in controlled conditions to tailor the silica porosity. The final material displayed a surface area of 711 m2 g−1 and a total pore volume of 0.93 cm3 g−1. The catalyst was evaluated with different pre-treatments in the direct synthesis of H 2 O 2 , where it exhibited structural resistance at the reaction conditions and a stable selectivity of 46 ± 1% towards H 2 O 2. [ABSTRACT FROM AUTHOR]

The reactivities of two model molecules, 3-methylthiophene (3MT) and benzothiophene (BT), representative of those contained in a FCC gasoline, was investigated over two Ni-promoted MoS 2 (NiMoS) bulk catalysts prepared according to two synthesis procedures, a metathesis-like one (NiMoS-M) and an innovative one including an in-situ Ni promotion (NiMoS-NG). The second procedure led to smaller NiMoS particles with a narrower size distribution and higher Ni promotion rate. Differences in the activity of the catalysts were observed for the transformation of 3MT and BT. BT was more reactive than 3MT over NiMoS-M whereas the reactivity of both sulfur molecules became similar over NiMoS-NG. The kinetic modeling indicated a higher adsorption constant of 3MT over NiMoS-NG than NiMoS-M and similar adsorption constant of BT on both catalysts. The results have been interpreted taking into account the differences of the catalyst properties in relation with the mechanisms involved in the transformation of both molecules. [Display omitted] ● Influence of synthesis procedures for NiMoS catalyst properties. ● Innovative synthesis of MoS 2 bulk catalysts with remarkable Ni promotion. ● Strong difference in reactivity of 3-methylthiophene and benzothiophene. ● Importance of coupled "experimental/kinetic modeling" studies. ● Importance of adsorption/reaction mechanisms of sulfur molecules for the catalyst efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Liquid and gas phase sulfidation conditions of MoO x /PANI hybrids result in different MoS x phases. • Active CoMoS phase content in the final catalysts deposited through a surface reaction using cobalt acetylacetonate depends on the nature of starting Mo based PANI materials. The formation of mixed sites is favored when Mo and Co sulfidations are simultaneous. • CoMoS/PANI showed much better catalytic activities than the CoMoS counterpart prepared without PANI. • HDS of 3-methylthiophene is correlated to the Co/Mo edges+corners atomic ratio as well as the HDS / HYD selectivity factor. Catalytic performances of promoted CoMoS catalysts were greatly improved via a synthesis strategy based on the structuration of the active phase using self-assembled PANI (Polyaniline) nanowires followed by an addition step of cobalt acetylacetonate on oxidic or sulfided Mo-based hybrids. Taking into account the different promotion levels, slabs lengths determined by XPS and TEM, the highest rate constants normalized by mol of (MoS 2) edges+corner in the hydrodesulfurization of 3-methylthiophene were obtained when Co(acac) 2 is deposited on a MoS 3 /PANI hybrid precursor. The normalized HDS rate constants for the different samples followed the increase in Co/Mo edges+corner atomic ratios whereas an optimum for HDS/HYD selectivity in the same ratio was observed. [ABSTRACT FROM AUTHOR]